Background: Dermoscopic features of congenital melanocytic nevi (CMN) have been mostly assessed by high-resolution video-dermoscopy. However, optical dermoscopy with the 10-fold magnification is largely available. In some instances, the differential diagnosis between large CMN and Becker nevus (BN) may be difficult.
Objective: The aims of this work were: (1) to assess by dermoscopy with the 10-fold magnification the morphological features which have been previously suggested as useful for the identification of CMN in high-resolution video-dermoscopy; (2) to search and point out the dermoscopic features of BN; (3) to explore dermoscopic differences between CMN and BN.
Methods: The subjects were observed among about 23,000 consecutive young men assessed at the Draft Council's Medical Unit of the Italian Navy in Taranto for compulsory recruitment and referred to the Department of Dermatology of the Italian Navy Hospital for dermatological examination. Lesions were examined by the same observer using a dermatoscope with a 10-fold magnification, and both the dermoscopic criteria stated by the international Consensus Net Meeting on Dermoscopy and dermoscopic features previously suggested as useful for the identification of CMN by video-dermoscopy were recorded in a predisposed patient's card.
Results: There were 127 male subjects, median age 19 years, with 127 CMN, measuring > or = 1.5 to < or = 19.9 cm in 78% and > or = 20 cm in 22% of cases, and 64 male subjects, median age 19 years, with 64 BN. In the sample of medium-sized and large CMN, dermoscopic features previously identified as characteristic of congenital lesions (i.e. target network, focal thickening of network lines, target globules, skin furrow hypopigmentation, focal hypopigmentation, hair follicles, perifollicular hypopigmentation, vessels and target vessels) were observed in sufficiently high rates. In the BN group, network, focal hypopigmentation, skin furrow hypopigmentation, hair follicles, perifollicular hypopigmentation and vessels were the main dermoscopic features. Focal thickening of network lines, globules, target globules, homogeneous diffuse pigmentation, hyperpigmented areas, blotches and target vessels were more frequently observed in CMN than in BN.
Conclusions: (1) The same dermoscopic features observed in small and medium-sized CMN by video-dermoscopy with high magnifications are also detectable in medium-sized and large CMN, employing the dermoscopy with the 10-fold magnification. (2) Network, focal, skin furrow and perifollicular hypopigmentation, hair follicles and vessels could be considered as peculiar dermoscopic features of BN. (3) Major differences in the frequency of dermoscopic characteristics were detected between CMN and BN, and dermoscopy seems to provide some diagnostic aid in differentiating CMN from BN in equivocal cases.
2006 S. Karger AG, Basel